when(mockDelegate.getReceiveBufferSize()).thenReturn(8192);
        when(mockDelegate.getMaximumBufferSize()).thenReturn(65536);
        when(mockDelegate.getTransactionBufferSize()).thenReturn(65024);
        when(mockDelegate.getBufferCacheSize()).thenReturn(16);
        when(mockDelegate.getNotifyBufferSize()).thenReturn(1024);

        // When
        int sendBufferSize = delegatingConfig.getSendBufferSize();

    cache.put(3, 20);
    cache.put(6, 2);
    cache.put(98, 45);
    cache.put(56, 76);
    cache.put(23, 84);

    // Replace the two present elements.
    cache.put(23, 20);
    cache.put(56, 49);
    cache.put(23, 2);
    cache.put(56, 4);

    // Expire the two present elements.
    fakeTicker.advance(1001, MILLISECONDS);

    Integer unused1 = cache.getIfPresent(23);